[Estrogens and synaptic plasticity].

Estrogens influence morphology of the brain not only in structures linked to reproductive cycle and reproductive behavior but also structure engaged in memory and cognitive functions. Estrogens stimulate synaptogenesis in pyramidal neurons of CA1 field of hippocampus. Increase in the number of spines on apical dendrites in rats occurs in the prostures phase of the cycle as well as exogenous estradiol application in ovariectomized females. The new synapses are enriched in NMDA receptor and it was found that their generation involves activation of NMDA receptors, PKA and CREB. Estradiol-induced synaptogenesis is accompanied by facilitation of LTP induction. Estradiol affects pyramidal cells of CA1 probably by inhibiting GABA-ergic interneurons. It also modulates unspecific activatory systems, which contribute significantly to neuroplasticity.